Low Blood Pressure

Also known as Hypotension
Low blood pressure is when blood flows through your blood vessels at lower than normal pressures.
Overview

Blood pressure is the force of blood pushing against the walls of your arteries as the heart pumps blood. It is usually described as two numbers: systolic and diastolic. The numbers record blood pressure in millimeters of mercury (mm Hg), with systolic listed above diastolic. For most adults, a healthy blood pressure is usually less than 120/80 mm Hg. Low blood pressure is blood pressure that is lower than 90/60 mm Hg.

Some people have low blood pressure all the time, and it is normal for them. Other people experience a sudden drop in blood pressure or have low blood pressure that may be linked to a health problem. Many systems of the body, including organs, hormones, and nerves, regulate blood pressure. For example, the autonomic nervous system sends the “fight-or-flight” signal that, depending on the situation, tells the heart and other systems in the body to increase or decrease blood pressure. Problems with the autonomic nervous system, such as in Parkinson’s disease, can cause low blood pressure.

Other causes of low blood pressure include medicines, bleeding, aging, and conditions such as dehydration, pregnancy, diabetes, and heart problems. Older adults have a higher risk for symptoms of low blood pressure, such as falling, fainting, or dizziness upon standing up or after a meal. Older adults are also more likely to develop low blood pressure as a side effect of medicines taken to control high blood pressure.

For many people, low blood pressure goes unnoticed. Others feel light-headed, confused, tired, or weak. You may have blurry vision, a headache, neck or back pain, nausea, or heart palpitations. Sitting down may relieve these symptoms. If blood pressure drops too low, the body’s vital organs do not get enough oxygen and nutrients. When this happens, low blood pressure can lead to shock, which requires immediate medical attention. Signs of shock include cold and sweaty skin, rapid breathing, a blue skin tone, or a weak and rapid pulse. If you notice signs of shock in yourself or someone else, call 9-1-1.

Your doctor will use a blood pressure test to diagnose low blood pressure. Other tests may include blood, urine, or imaging tests and a tilt table test if you faint often. You may not need treatment for low blood pressure. Depending on your signs and symptoms, treatment may include drinking more fluids, taking medicines to raise your blood pressure, or adjusting medicines that cause low blood pressure. Recommended lifestyle changes include changing what and how you eat and how you sit and stand up. Your doctor may also recommend compression stockings if you have to stand for long periods.

Visit Low Blood Pressure for more information about this topic.

Research for Your Health

The NHLBI is part of the U.S. Department of Health and Human Services’ National Institutes of Health (NIH)—the Nation’s biomedical research agency that makes important scientific discovery to improve health and save lives. We are committed to advancing science and translating discoveries into clinical practice to promote the prevention and treatment of heart, lung, blood, and sleep disorders, including problems associated with low blood pressure. Learn about current and future NHLBI efforts to improve health through research and scientific discovery.

Improving health with current research
- Low Blood Pressure

Learn about the following ways the NHLBI continues to translate current research into improved health for people with abnormally low blood pressure. Research on this topic is part of the NHLBI’s broader commitment to advancing heart and vascular disease scientific discovery.

  • Testing Treatments for Cardiac Arrest and Trauma. The Resuscitation Outcomes Consortium (ROC) clinical trial network tested treatments to address high morbidity and mortality rates from out-of-hospital cardiac arrest and severe traumatic injury. ROC investigators compared different strategies for supplemental fluids in trauma patients who have low blood pressure. Other ROC studies found a link between low blood pressure readings and the need for emergency procedures.
  • Understanding How Low Blood Pressure Affects Diverse Populations. NHLBI-supported researchers are studying low blood pressure in different populations. Investigators in the NHLBI’s Atherosclerosis Risk in Communities Study (ARIC) found that people who have low blood pressure when standing up, known as orthostatic hypotension, are at higher risk for stroke. In a follow-up study of NHLBI’s Honolulu Heart Program, researchers found older Japanese men who had orthostatic hypotension were nearly twice as likely to die within the next four years as those who did not have orthostatic hypotension. NHLBI’s Cardiovascular Health Study (CHS) found that orthostatic hypotension was common in older adults, increases with age, and is linked to cardiovascular diseases.

Learn about some of the pioneering research contributions we have made over the years that have improved clinical care.

Advancing research for improved health
- Low Blood Pressure

In support of our mission, we are committed to advancing research on low blood pressure in part through the following ways.

Learn about exciting research areas the NHLBI is exploring about low blood pressure.

Participate in NHLBI Clinical Trials

We lead or sponsor research on low blood pressure. See whether you or someone you know is eligible to participate in our clinical trials.

Do you know someone whose child was just born preterm?

This study aims to understand why some premature babies have low blood pressure by studying heart and lung changes during the first week of life in preterm babies who do or do not have low blood pressure. Researchers hope the results will improve monitoring of newborns’ blood circulation patterns. To participate in this study, your newborn must have weighed 2.2 pounds or less at birth, be less than 1 week old, and be receiving care in a neonatal intensive care unit. This study is located in Houston, Texas.

Have you been diagnosed with orthostatic intolerance?

This study aims to find out how the body’s regulation of basic functions, such as heart rate and blood pressure, is altered in people who have orthostatic intolerance. This condition, which has an unknown cause, is characterized by a racing heartbeat, dizziness, lightheadedness, and other symptoms that occur when a person stands up. To participate in this study, you must be between 18 and 80 years old and have orthostatic intolerance. This study is located in Nashville, Tennessee.

More Information

After reading our Low Blood Pressure Health Topic, you may be interested in additional information found in the following resources.

Non-NHLBI resources
- Low Blood Pressure